Field of the Invention
The present invention relates to an image pickup apparatus and a method of controlling an image pickup apparatus.
Description of the Related Art
In recent years, further improvements of performance such as a higher resolution, continuous photographing at higher speed, and an improvement of a frame rate of a motion image are required for image pickup apparatus.
In order to satisfy the above-mentioned requirement, a larger amount of data than needed hitherto is required to be processed at high speed in the image pickup apparatus.
When a capacity (band) of a transmission path is increased to transmit the large amount of data, however, costs disadvantageously increase.
In Japanese Patent Application Laid-Open No. 2014-103543, there is disclosed a technology involving transmitting image data compressed by a compression unit, which is included in an image pickup element and configured to compress the image data, through a bus to an image processing apparatus and performing expansion processing on the compressed image data in the image processing apparatus. In Japanese Patent Application Laid-Open No. 2014-103543, a large amount of data can be transmitted without using a bus having a large transmission capacity.
On the other hand, image pickup apparatus having an autofocus (AF) function have been known hitherto. Various systems have been proposed as autofocus systems. As one of the various autofocus systems, there has been proposed a technology of performing focus detection by a computation performed based on a signal acquired by an image pickup element.
For example, in contrast autofocus, a signal is acquired by an image pickup element while driving a lens so that the focus detection is performed based on a change in contrast of the signal for each lens position.
Further, in Japanese Patent Application Laid-Open No. 2013-072906, the following image pickup apparatus is described. Specifically, a parallax image is acquired by using an image pickup element in which each pixel having a plurality of photoelectric converters is located under one microlens. The focus detection is performed by a phase-difference computation using the thus obtained parallax image.